The present invention relates to rotating electric machines and more especially concerns synchronous machines, such as alternators for motor vehicles, traction motors or the like.
Among the known machines, mention may be made of machines employing excitation by coils mounted in the rotor, machines employing excitation by magnets mounted in the rotor and machines employing double excitation by coils and magnets mounted in the rotor.
Such machines are described in particular in patent application FR-97 03 429 filed on Mar. 20, 1997 by the Centre National de la Recherche Scientifique [French National Centre for Scientific Research].
Such a machine comprising a rotor whose magnetic circuit carries excitation elements and a stator whose magnetic circuit carries a stator coil, is characterized in that the magnetic circuit of the rotor comprises, mounted on a shaft, end flanges and at least one toothed disc arranged between the end flanges, the teeth of the toothed disc being uniformly distributed at its periphery and at least one annular piece mounted on the end flanges and furnished with apertures uniformly distributed at its periphery and in each of which is engaged a tooth of at least one toothed disc, the end flanges and said at least one toothed disc defining between them, spaces in which excitation elements are housed.
Furthermore, patent application FR-97 05 030 filed on Apr. 23, 1997 by the Centre National de la Recherche Scientifique describes a rotating electric machine of the double excitation type mounted on a shaft comprising a rotor whose magnetic circuit carries at least one excitation element and a stator whose magnetic circuit carries a stator coil, characterized in that said at least one excitation element comprises at least one annular magnet associated with at least two discs each furnished with radial teeth uniformly distributed at their periphery and at least one annular piece furnished with apertures in each of which is engaged without contact, a tooth of at least one toothed disc, and in that the magnetic circuit of the stator comprises an even number at least equal to two annular magnetic circuit elements, at least one stator excitation coil being disposed between at least two neighboring elements from among said magnetic circuit elements.
Although giving acceptable results and allowing the elimination of brushes, the machines of the aforesaid type exhibit a low per-magnet rotor excitation active gap area.
The invention aims to create a double-excitation machine which while exhibiting the same advantages as the aforesaid machine, in particular as regards adjustment via double excitation and the elimination of brushes, comprises enhanced per-magnet rotor excitation.
Its subject is therefore a rotating electric machine with double excitation comprising a rotor and a stator whose magnetic circuit carries a stator coil, in which machine the stator comprises an annular magnetic core and at least one excitation coil, the stator coil being wound on the core, the assembly being arranged in at least one magnetic ring in contact with the outer surface of the stator core, said at least one ring comprising at least one radial end rim, and the rotor comprises a magnetic circuit exhibiting peripheral portions, said radial end rims of said at least one magnetic ring of the stator defining, with the peripheral portions of the magnetic circuit of the rotor, gaps forming flux return paths, characterized in that the rotor comprises magnetic end flanges whose peripheral portions define with the radial end rims of said at least one magnetic ring of the stator, said flux return gaps and arranged between the magnetic end flanges, a magnetic core provided with radial teeth uniformly distributed at its periphery, annular magnets arranged on either side of the axial ends of the core and applied against the core by the magnetic end flanges and several magnetic pieces for interlinking the end flanges, formed of bars for linking the end flanges housed in the spaces between the radial teeth of the magnetic core.